To continue your business analysis of the situation, two other important aspects to consider are whether the (perceived) net benefit outweighs the opportunity cost, and whether the net benefit in that individual position also equates to a benefit across the team.
I'm not convinced on either aspect. There are other areas of the team that need addressing long before we look for marginal gains in the goalkeeper, and if we accept for talking sake there is an improvement, we are talking marginal gains. Whilst Leno cleared had some better attributes than Ramsdale, it was a transformative change. The gap between Ramsdale and Raya is miniscule in comparison.
Which brings me to my second point - each change brings an adaption period and extra pressure on players to build understandings with those around them. Havertz for Xhaka, adding Rice, and intending to add Timber were all significant changes to a team already still developing. It was never going to be an easy transition to incorporate three new players and remodel the midfield at once. Unnecessarily complicating that further by changing the keeper is foolish, and negates any benefit it might have brought the wider team as far as I can see. I'm not saying the keeper shouldn't have been addressed, but it was the wrong time to do it. Let the team settle. Let the transformative signings bed in, new patterns form, and chemistry develop. Then work on the marginal issues. It was too much at one time.
These questions aren't, or shouldn't, just be about individuals and values, they should be about sequencing these issues and having a coherent plan for squad development in 2/3/4 years time as well as the present. Given that I think Raya is a mistake.
